This invention relates to methods of forming local interconnects, and to integrated circuitry which includes local interconnects.
The reduction in memory cell and other circuit size in high density dynamic random access memories (DRAMs) and other circuitry is a continuing goal in semiconductor fabrication. Implementing electric circuits involves connecting isolated devices through specific electric paths. When fabricating silicon and other semiconductive materials into integrated circuits, conductive devices built into semiconductive substrates typically need to be isolated from one another. Such isolation typically occurs in the form of either trench and refill field isolation regions or LOCOS grown field oxide.
Conductive lines, for example transistor gate lines, are formed over bulk semiconductor substrates. Some lines run globally over large areas of the semiconductor substrate. Others are much shorter and associated with very small portions of the integrated circuitry, and are typically referred to as local interconnects. This invention was principally motivated in making processing improvements in the fabrication of local interconnects, and particularly in the fabrication of SRAM circuitry local interconnects and embedded technologies, although the invention is not so limited.
The invention includes integrated circuitry employing local interconnects, and methods of forming local interconnects. In one implementation, a first dielectric layer is formed over a first transistor gate and a second transistor source/drain region. Contact openings are formed in the first dielectric layer to the first transistor gate and to the second transistor source/drain region. A second dielectric layer is formed over the first dielectric layer and to within the contact openings. The second dielectric layer is etched selectively relative to the first dielectric layer to form at least a portion of a local interconnect outline within the second dielectric layer to extend between the first transistor gate and the second transistor source/drain region. The etching removes at least some of the second dielectric layer within the contact openings. Conductive material is formed within the local interconnect outline within the second dielectric layer which electrically connects the first transistor gate with the second transistor source/drain region.
In one implementation, a conductive silicide is formed on the first transistor gate and on the second transistor source/drain region in at least one common step. A dielectric layer is formed over the first transistor gate silicide and the second transistor source/drain region silicide. The dielectric layer is etched to form at least a portion of a local interconnect outline therewithin to extend between the first transistor gate suicide and the second transistor source/drain region silicide. Conductive material is formed within the local interconnect outline within the dielectric layer and on the first transistor gate silicide and on the second transistor source/drain region silicide to electrically connect the first transistor gate with the second transistor source/drain region.
In one implementation, integrated circuitry includes a substrate comprising first and second transistor gates. A source/drain region is received proximate the second transistor gate. The first transistor gate includes conductively doped semiconductive material and a conductive silicide received elevationally outward thereof and in electrical connection therewith. The semiconductive material and the silicide have respective elevationally outermost surfaces. The first transistor gate has opposing sidewalls which include the semiconductive material and the silicide. A pair of insulative sidewall spacers is received over the first transistor gate sidewalls. The sidewall spacers have respective uppermost surfaces which are substantially elevationally coincident with the uppermost surface of the semiconductive material. A conductive local interconnect electrically connects the first transistor gate silicide with the source/drain region proximate the second transistor gate.